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1.
St. Lawrence and Atlantic Railroad
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It crosses the Canada–US border at Norton, Vermont, and is owned by short line operator Genesee and Wyoming. The line was built by the Atlantic and St. Lawrence Railroad in the U. S. major communities served include Portland and Lewiston in Maine, Berlin, New Hampshire, Island Pond, Vermont, and Sherbrooke and Montreal in Quebec. Milepost 0, Portland terminal facilities including wharves, grain elevators, Portland Company shops, feldspar was mined, processed and loaded here for the manufacture of porcelain from 1925 to 1988. Station built in 1851, enlarged in 1879, and closed in 1967 was razed in 1968, Portland was desperate to connect its ice-free port with Montreal, and Maine was at risk of being eclipsed by a similar proposal running from nearby Boston, Massachusetts. Montreal saw an advantage in linking with the port at Portland. William Pitt Preble was the railroads first President, the line was originally built to the Portland gauge of 5 ft 6 in. Construction started in Portland on July 4,1846, the first section, from Portland to Yarmouth, opened July 20,1848. Further extensions up the Royal River to Danville opened in October,1848, construction then proceeded up the Little Androscoggin River to Oxford in September,1849, and Paris in March,1850. Construction was then completed down the Alder River to the Androscoggin River at Bethel in March,1851, simultaneous construction of Portland gauge connecting railways occurred from Danville and Mechanic Falls. Sections into and within New Hampshire opened to Gorham on July 23,1851 and Northumberland July 12,1852, and the full distance to Island Pond, Vermont on January 29,1853. The St. Lawrence and Atlantic Railway was chartered to build the part of the line in Quebec, regular operations began April 4,1853 between Montreal and Portland. Four months later, on August 5,1853 the Grand Trunk Railway leased the two companies, giving the Toronto-Montreal line an extension east to Portland, a branch was also built from Richmond, Quebec northeast to Point Levi, across the St. Lawrence River from Quebec City. Grand Trunk enlarged their waterfront facilities at Portland by purchasing land from Henry Wadsworth Longfellow, the locomotives burned wood exclusively until the cost of seasoned firewood increased during the winter of 1871-72 to make other fuels competitive. Peat from Quebec was used briefly before coal became the standard, coal was used exclusively between Portland and Gorham by 1879, but use of wood continued for a few more years north of Gorham. Interchange with standard gauge railroads became a problem during the 1860s, Grand Trunk equipped approximately 1,000 freight cars with experimental sliding-wheels in 1863 at company shops in Sarnia, Ontario, and Pointe-Saint-Charles in Montreal. Gauge could be adjusted by removing and inserting axle pins on special tapered-gauge track segments at interchange points, safety problems were reported despite high maintenance costs. All lines west of Montreal were converted to standard gauge on October 3 and 4,1873, Grand Trunk purchased 200 standard gauge locomotives and converted 135 old locomotives. Ten thousand standard gauge bogies were purchased for conversion of freight cars, the railway from Portland to Montreal was standard-gauged in September,1874

2.
Yarmouth, Maine
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Yarmouth is a town in Cumberland County, Maine, United States, located twelve miles north of the states largest city, Portland. The town was settled in 1636 and incorporated in 1849 and its population was 8,349 in the 2010 census. As of 2015s estimation, this is about 0. 6% of Maines total population, Yarmouth is part of the Portland–South Portland-Biddeford Metropolitan Statistical Area. The towns proximity to the Atlantic Ocean and its location on the banks of the Royal River, ships were built in the harbor mainly between 1818 and the 1870s, at which point demand declined dramatically. Meanwhile, the Royal Rivers four waterfalls within Yarmouth, whose Main Street sits about 45 feet above sea level, the annual Yarmouth Clam Festival attracts around 120,000 people over the course of the three-day weekend. Today, Yarmouth is a dining destination, with fourteen sit-down restaurants. This equates to an average of just over one restaurant per square mile of land area, Yarmouth is easily accessed via two exits on each side of Interstate 295. U. S. Route 1 also passes through the town to the west of I-295 and it has been designated a Tree City USA community every year since 1979. According to the United States Census Bureau, the town has an area of 22.94 square miles. Yarmouth is nearly square in form, and is bisected by the Royal River. The Cousins River separates it from Freeport to the northeast, Freeport and Pownal bound it to the east, North Yarmouth to the north, Cumberland to the west, and Casco Bay to the south. Also included as part of the town are Cousins Island, Lanes Island, Great and Little Moshier islands, the Royal River appealed to settlers because its four waterfalls and 60-foot rise within a mile of navigable water provided four potential waterpower sites. In 1674, the first sawmill, of Sayward & Gedney, was built on the side of the First Falls. Since 1674,57 mills and several factories stood along the shores of the river, the Native Americans called the First Falls Pumgustuk, which means head of tide. In addition to the 1674 sawmill, this was the site of the first grist mill — Lower Grist Mills — built in 1813 and whose foundations support the overlook of todays Grist Mill Park. The mill, which was in business for 36 years, ground wheat, between 1870 and 1885, it was the site of Ansel Lorings grist mill, named Yarmouth Flour Mill. The first mill to go up on the side of the river was Seabury & Mitchells grist mill in 1729. By 1874, the East Main Street bridge was flanked by a grist mill, saw mill, a store, in 1911, Yarmouth Manufacturing Companys electric power plant was built on the site of Craigs sawmill

3.
Canon Inc.
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It is headquartered in Ōta, Tokyo, Japan. Canon has a listing on the Tokyo Stock Exchange and is a constituent of the TOPIX index. It has a listing on the New York Stock Exchange. At the beginning of 2015, Canon was the tenth largest public company in Japan when measured by market capitalization, the company was originally named Seikikōgaku kenkyūsho. In 1934 it produced the Kwanon, a prototype for Japan’s first-ever 35 mm camera with a plane based shutter. In 1947 the company name was changed to Canon Camera Co. Inc. shortened to Canon Inc. in 1969, the name Canon comes from Buddhist bodhisattva Guan Yin, previously transliterated as Kuanyin, Kwannon, or Kwanon in English. The origins of Canon date back to the founding of Precision Optical Instruments Laboratory in Japan in 1937 by Takeshi Mitarai, Goro Yoshida, Saburo Uchida and Takeo Maeda. During its early years the company did not have any facilities to produce its own optical glass, between 1933 and 1936 ‘The Kwanon’, a copy of the Leica design, Japan’s first 35 mm focal plane-shutter camera, was developed in prototype form. In 1940 Canon developed Japans first indirect X-ray camera, Canon introduced a field zoom lens for television broadcasting in 1958 and in 1959 introduced the Reflex Zoom 8, the world’s first movie camera with a zoom lens, and the Canonflex. In 1961 Canon introduced the Rangefinder camera, Canon 7, in 1965 Canon introduced the Canon Pellix, a single lens reflex camera with a semi-transparent stationary mirror which enabled the taking of pictures through the mirror. In 1971 Canon introduced the F-1, a high-end SLR camera, in 1976 Canon launched the AE-1, the world’s first camera with an embedded micro-computer. In 1982 Wildlife as Canon Sees It print ads first appeared in National Geographic magazine, Canon introduced the world’s first Inkjet printer using bubble jet technology in 1985. Canon introduced Canon Electro-Optical System in 1987, named after the goddess of the dawn, EOS650 autofocus SLR camera is introduced. Also in 1987 the Canon Foundation was established, in 1988 Canon introduced Kyosei philosophy. The EOS1 Flagship Professional SLR line was launched in 1989, in the same year the EOS RT, the worlds first AF SLR with a fixed, semi-transparent pellicle mirror, was unveiled. In 1992 Canon launched the EOS5, the camera with eye-controlled AF. In 1995 Canon introduced the first commercially available SLR lens with image stabilization. EOS-1N RS, the worlds fastest AF SLR camera with a shooting speed of 10 frame/s at the time

4.
Canon Digital IXUS
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The Digital IXUS is a series of digital cameras released by Canon. It is a line of cameras, originally based on the design of Canons IXUS/IXY/ELPH line of APS cameras. This article uses the Digital IXUS model names unless otherwise stated, the comparison tables in this article list equivalent IXY Digital and PowerShot Digital ELPH model names. Canons PowerShot A and S line of the time were being made as small as contemporary technology allowed, the first Digital IXUS, released in June 2000 fitted the technology of the PowerShot S10 into a body similar to the APS IXUS II. Between 2003 and 2004, starting with the Digital IXUS II, the Ixus 900Ti was the first in a series of Ixus and S-series cameras that feature the Digic image processors and larger than average sensors as fitted to the advanced PowerShot G-series cameras. The Ixus / S-series and the equivalent G-series models are listed below, Ixus 960IS* / PowerShot G9 / Digic III /12. 1MP4000 ×3000 1/1. 7″ CCD. Ixus 980IS / PowerShot G10 / Digic 4 /14. 7MP4416 ×3312 1/1. 7″ CCD, PowerShot S90, S95, S200 / PowerShot G11, G12 / Digic 4 / 10MP3648 ×2736 1/1. 7″ CCD. PowerShot S100, S110 / PowerShot G15 / Digic 5 /12. 1MP 4000×3000 1/1.7 CMOS, powershot S120 / PowerShot G16 / Digic 6 /12. 1MP 4000×3000 1/1.7 CMOS. The same camera models are released in Europe, the US, the cameras themselves are identical apart from the front fascia, according to the parts lists. The Canon model number on the bottom is consistent between marketing names, all models use lithium ion batteries of Canon proprietary design, though third-party equivalents are readily available. All models introduced before 2010 use RGBG Bayer filter CCD sensors made by Sony, IXUS300 HS/PowerShot Digital ELPH SD4000 IS/IXY 30S introduced in May 2010 and all following models have back-illuminated CMOS sensor. Raw image files are not accessible without the use of third party such as CHDK. In 2010 Canon dropped the prefix Digital as well as suffix IS from the names of the new models e. g. IXUS105, a similar change was applied to the IXY-series names used in the Japanese market. The United States market naming was simplified in 2011, Digital, newer US and European model carry HS suffix, that stands for high sensitivity. The Digital IXUS series slots above the PowerShot A in Canons point-and-shoot lineup, the PowerShot Digital ELPH using CF have Sxxx model number. Canon issued a recall in October 2006 adding these to their recall list, the damaged CCD displays purple or blueish, distorted or possibly no image at all. The menu and pictures taken prior to the CCD disconnect will still display normally, the camera also incorrectly reports a problem with the memory card. This problem can be overcome by removing both the main battery as well as the small internal battery

5.
Shutter speed
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The amount of light that reaches the film or image sensor is proportional to the exposure time. 1/500th of a second will let half as much light in as 1/250th, the cameras shutter speed, the lenss aperture, and the scenes luminance together determine the amount of light that reaches the film or sensor. Exposure value is a quantity that accounts for the shutter speed and this will achieve a good exposure when all the details of the scene are legible on the photograph. Too much light let into the results in an overly pale image while too little light will result in an overly dark image. Multiple combinations of speed and f-number can give the same exposure value. According to exposure value formula, doubling the exposure time doubles the amount of light, for example, f/8 lets 4 times more light into the camera as f/16 does. In addition to its effect on exposure, the speed changes the way movement appears in photographs. Very short shutter speeds can be used to freeze fast-moving subjects, very long shutter speeds are used to intentionally blur a moving subject for effect. Short exposure times are called fast, and long exposure times slow. Adjustments to the aperture need to be compensated by changes of the speed to keep the same exposure. The agreed standards for shutter speeds are, With this scale, camera shutters often include one or two other settings for making very long exposures, B keeps the shutter open as long as the shutter release is held. T keeps the open until the shutter release is pressed again. The ability of the photographer to take images without noticeable blurring by camera movement is an important parameter in the choice of the slowest possible speed for a handheld camera. Through practice and special techniques such as bracing the camera, arms, or body to minimize movement, using a monopod or a tripod. If a shutter speed is too slow for hand holding, a support, usually a tripod. Image stabilization on digital cameras or lenses can often permit the use of shutter speeds 3–4 stops slower, Shutter priority refers to a shooting mode used in cameras. It allows the photographer to choose a shutter speed setting and allow the camera to decide the correct aperture and this is sometimes referred to as Shutter Speed Priority Auto Exposure, or TV mode, S mode on Nikons and most other brands. Shutter speed is one of methods used to control the amount of light recorded by the cameras digital sensor or film

6.
Film speed
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Film speed is the measure of a photographic films sensitivity to light, determined by sensitometry and measured on various numerical scales, the most recent being the ISO system. A closely related ISO system is used to measure the sensitivity of digital imaging systems, highly sensitive films are correspondingly termed fast films. In both digital and film photography, the reduction of exposure corresponding to use of higher sensitivities generally leads to reduced image quality, in short, the higher the sensitivity, the grainier the image will be. Ultimately sensitivity is limited by the efficiency of the film or sensor. The speed of the emulsion was then expressed in degrees Warnerke corresponding with the last number visible on the plate after development. Each number represented an increase of 1/3 in speed, typical speeds were between 10° and 25° Warnerke at the time. The concept, however, was built upon in 1900 by Henry Chapman Jones in the development of his plate tester. In their system, speed numbers were inversely proportional to the exposure required, for example, an emulsion rated at 250 H&D would require ten times the exposure of an emulsion rated at 2500 H&D. The methods to determine the sensitivity were later modified in 1925, the H&D system was officially accepted as a standard in the former Soviet Union from 1928 until September 1951, when it was superseded by GOST 2817-50. The Scheinergrade system was devised by the German astronomer Julius Scheiner in 1894 originally as a method of comparing the speeds of plates used for astronomical photography, Scheiners system rated the speed of a plate by the least exposure to produce a visible darkening upon development. ≈2 The system was extended to cover larger ranges and some of its practical shortcomings were addressed by the Austrian scientist Josef Maria Eder. Scheiners system was abandoned in Germany, when the standardized DIN system was introduced in 1934. In various forms, it continued to be in use in other countries for some time. The DIN system, officially DIN standard 4512 by Deutsches Institut für Normung, was published in January 1934, International Congress of Photography held in Dresden from August 3 to 8,1931. The DIN system was inspired by Scheiners system, but the sensitivities were represented as the base 10 logarithm of the sensitivity multiplied by 10, similar to decibels. Thus an increase of 20° represented an increase in sensitivity. ≈3 /10 As in the Scheiner system, speeds were expressed in degrees, originally the sensitivity was written as a fraction with tenths, where the resultant value 1.8 represented the relative base 10 logarithm of the speed. Tenths were later abandoned with DIN4512, 1957-11, and the example above would be written as 18° DIN, the degree symbol was finally dropped with DIN4512, 1961-10

7.
Focal length
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The focal length of an optical system is a measure of how strongly the system converges or diverges light. For an optical system in air, it is the distance over which initially collimated rays are brought to a focus. A system with a focal length has greater optical power than one with a long focal length. For a thin lens in air, the length is the distance from the center of the lens to the principal foci of the lens. For a converging lens, the length is positive, and is the distance at which a beam of collimated light will be focused to a single spot. For a diverging lens, the length is negative, and is the distance to the point from which a collimated beam appears to be diverging after passing through the lens. The focal length of a lens can be easily measured by using it to form an image of a distant light source on a screen. The lens is moved until an image is formed on the screen. In this case 1/u is negligible, and the length is then given by f ≈ v. Back focal length or back focal distance is the distance from the vertex of the last optical surface of the system to the focal point. For an optical system in air, the focal length gives the distance from the front. If the surrounding medium is not air, then the distance is multiplied by the index of the medium. Some authors call these distances the front/rear focal lengths, distinguishing them from the front/rear focal distances, defined above. In general, the length or EFL is the value that describes the ability of the optical system to focus light. The other parameters are used in determining where an image will be formed for an object position. The quantity 1/f is also known as the power of the lens. The corresponding front focal distance is, FFD = f, in the sign convention used here, the value of R1 will be positive if the first lens surface is convex, and negative if it is concave. The value of R2 is negative if the surface is convex

8.
Flash (photography)
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A flash is a device used in photography producing a flash of artificial light at a color temperature of about 5500 K to help illuminate a scene. A major purpose of a flash is to illuminate a dark scene, other uses are capturing quickly moving objects or changing the quality of light. Flash refers either to the flash of light itself or to the flash unit discharging the light. Most current flash units are electronic, having evolved from single-use flashbulbs, modern cameras often activate flash units automatically. Flash units are built directly into a camera. Some cameras allow separate flash units to be mounted via an accessory mount bracket. In professional studio equipment, flashes may be large, standalone units, or studio strobes, studies of magnesium by Bunsen and Roscoe in 1859 showed that burning this metal produced a light with similar qualities to daylight. The potential application to photography inspired Edward Sonstadt to investigate methods of manufacturing magnesium so that it would burn reliably for this use and he applied for patents in 1862 and by 1864 had started the Manchester Magnesium Company with Edward Mellor. It also had the benefit of being a simpler and cheaper process than making round wire, mather was also credited with the invention of a holder for the ribbon, which formed a lamp to burn it in. The packaging also implies that the ribbon was not necessarily broken off before being ignited. An alternative to ribbon was flash powder, a mixture of powder and potassium chlorate, introduced by its German inventors Adolf Miethe. A measured amount was put into a pan or trough and ignited by hand, producing a brilliant flash of light, along with the smoke. This could be an activity, especially if the flash powder was damp. An electrically triggered flash lamp was invented by Joshua Lionel Cowen in 1899 and his patent describes a device for igniting photographers’ flash powder by using dry cell batteries to heat a wire fuse. Variations and alternatives were touted from time to time and a few found a measure of success in the marketplace, especially for amateur use. The use of powder in an open lamp was replaced by flashbulbs, magnesium filaments were contained in bulbs filled with oxygen gas. Manufactured flashbulbs were first produced commercially in Germany in 1929, such a bulb could only be used once, and was too hot to handle immediately after use, but the confinement of what would otherwise have amounted to a small explosion was an important advance. A later innovation was the coating of flashbulbs with a film to maintain bulb integrity in the event of the glass shattering during the flash

9.
Color balance
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In photography and image processing, color balance is the global adjustment of the intensities of the colors. An important goal of this adjustment is to specific colors – particularly neutral colors – correctly. Hence, the method is sometimes called gray balance, neutral balance. Color balance changes the mixture of colors in an image and is used for color correction. Generalized versions of color balance are used to correct colors other than neutrals or to change them for effect. Image data acquired by sensors – either film or electronic image sensors – must be transformed from the values to new values that are appropriate for color reproduction or display. In film photography, color balance is achieved by using color correction filters over the lights or on the camera lens. It is particularly important that neutral colors in a scene appear neutral in the reproduction, most digital cameras have means to select color correction based on the type of scene lighting, using either manual lighting selection, automatic white balance, or custom white balance. The algorithms for these processes perform generalized chromatic adaptation, many methods exist for color balancing. Setting a button on a camera is a way for the user to indicate to the processor the nature of the scene lighting, another option on some cameras is a button which one may press when the camera is pointed at a gray card or other neutral colored object. This captures an image of the ambient light, which enables a digital camera to set the color balance for that light. There is a literature on how one might estimate the ambient lighting from the camera data. A variety of algorithms have been proposed, and the quality of these has been debated, a few examples and examination of the references therein will lead the reader to many others. Examples are Retinex, a neural network or a Bayesian method. Color balancing an image not only the neutrals, but other colors as well. An image that is not color balanced is said to have a color cast, Color balancing may be thought in terms of removing this color cast. Color balance is related to color constancy. Algorithms and techniques used to color constancy are frequently used for color balancing

10.
Digital zoom
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Digital zoom is a method of decreasing the apparent angle of view of a digital photographic or video image. It is accomplished electronically, with no adjustment of the cameras optics, in the former case, digital zoom tends to be superior to enlargement in post-processing, because the camera may apply its interpolation before detail is lost to compression. In the latter case, resizing in post-production yields results equal or superior to digital zoom, modest camera phones use only digital zoom and have no optical zoom at all. Usually cameras have an optical lens, but apply digital zoom automatically once its longest optical focal length has been reached. Professional cameras generally do not feature digital zoom, Digital zoom use the center area of the optical image to enlarge the image. By reducing the MP image size, using digital zoom can be done without image deterioration and some cameras has Undeteriorated image mode or at least has Image deterioration indicator. The table below give Undeteriorated zoom limit for some MP image size of a camera with Optical zoom 24x and Digital zoom 4x for its maximum capability, Note. The table above has also shown that from 3MP jumps directly too much too VGA and this camera has no option of 2MP and 1. 3MP, but other cameras have it. When using digital zoom for video, the camera can take up to 382. 6x magnification in VGA with Deteriorated image quality, but because video take multiframes per second, so between Deteriorated image quality and Undeteriorated image quality will be not much different. Nowadays cameras usually have iZoom with usually additional magnification 2x of its optical zoom, the iZoom use only center of the lens and not make any interpolation to original full resolution, so it save its good images quality in reduced resolution. The terms among camera manufacturers are “Smart Zoom”, “Safe Zoom”, there is also camera with digital zoom 7. 2x and smartzoom with approximately 30x total zoom for 7MP from 16MP total resolution and also 144x total zoom for VGA 640x480. Some photographers purposefully employ digital zoom for the low fidelity appearance of the images it produces. This community thinks that poor quality photographs imply the carelessness of the photographer and thus, the notion that it is possible to achieve authenticity through pre-meditated carelessness also inspires Lo-fi music. Image scaling Teleside converter - a secondary lens made for fixed lenses that increases the focal length, uses as a filter Zoom lens

11.
F-number
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The f-number of an optical system such as a camera lens is the ratio of the systems focal length to the diameter of the entrance pupil. It is a number that is a quantitative measure of lens speed. It is also known as the ratio, f-ratio, f-stop. The f-number is commonly indicated using a hooked f with the format f/N, the f-number N or f# is given by, N = f D where f is the focal length, and D is the diameter of the entrance pupil. It is customary to write f-numbers preceded by f/, which forms a mathematical expression of the pupil diameter in terms of f and N. Ignoring differences in light transmission efficiency, a lens with a greater f-number projects darker images, the brightness of the projected image relative to the brightness of the scene in the lenss field of view decreases with the square of the f-number. Doubling the f-number decreases the brightness by a factor of four. To maintain the same photographic exposure when doubling the f-number, the time would need to be four times as long. Most lenses have a diaphragm, which changes the size of the aperture stop. The entrance pupil diameter is not necessarily equal to the aperture stop diameter, a 100 mm focal length f/4 lens has an entrance pupil diameter of 25 mm. A200 mm focal length f/4 lens has a pupil diameter of 50 mm. The 200 mm lenss entrance pupil has four times the area of the 100 mm lenss entrance pupil, a T-stop is an f-number adjusted to account for light transmission efficiency. The word stop is sometimes confusing due to its multiple meanings, a stop can be a physical object, an opaque part of an optical system that blocks certain rays. In photography, stops are also a used to quantify ratios of light or exposure. The one-stop unit is known as the EV unit. On a camera, the setting is traditionally adjusted in discrete steps. Each stop is marked with its corresponding f-number, and represents a halving of the light intensity from the previous stop. This corresponds to a decrease of the pupil and aperture diameters by a factor of 1/2 or about 0.7071, each element in the sequence is one stop lower than the element to its left, and one stop higher than the element to its right

12.
Exposure compensation
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Factors considered may include unusual lighting distribution, variations within a camera system, filters, non-standard processing, or intended underexposure or overexposure. Cinematographers may also apply exposure compensation for changes in angle or film speed. Most DSLR cameras have a display whereby the photographer can set the camera to either over or under expose the subject by up to three f-stops in 1/3rd stop intervals. Each number on the scale represents one f-stop, decreasing the exposure by one f-stop will halve the amount of light reaching the sensor, the dots in between the numbers represent 1/3rd of an f-stop. In photography, some cameras include exposure compensation as a feature to allow the user to adjust the automatically calculated exposure, camera exposure compensation is commonly stated in terms of EV units,1 EV is equal to one exposure step, corresponding to a doubling of exposure. Exposure can be adjusted by changing either the lens f-number or the exposure time, if the mode is aperture priority, exposure compensation changes the exposure time, if the mode is shutter priority, the f-number is changed. If a flash is being used, some cameras will adjust it as well, the earliest reflected-light exposure meters were wide-angle, averaging types, measuring the average scene luminance. When measuring a scene with atypical distribution of light and dark elements, or an element that is lighter or darker than a middle tone. For example, a scene with predominantly light tones often will be underexposed and that both scenes require the same exposure, regardless of the meter indication, becomes obvious from a scene that includes both a white horse and a black horse. A photographer usually can recognize the difference between a horse and a black horse, a meter usually cannot. When metering a white horse, a photographer can apply exposure compensation so that the horse is rendered as white. Many modern cameras incorporate metering systems that measure scene contrast as well as average luminance, in scenes with very unusual lighting, however, these metering systems sometimes cannot match the judgment of a skilled photographer, so exposure compensation still may be needed. An early application of compensation was the Zone System developed by Ansel Adams. Developed for black-and-white film, the Zone System divided luminance into 11 zones, with Zone 0 representing pure black, the meter indication would place whatever was metered on Zone V, a medium gray. The meter indication, however, remains Zone V, the Zone System is a very specialized form of exposure compensation, and is used most effectively when metering individual scene elements, such as a sunlit rock or the bark of a tree in shade. Many cameras incorporate narrow-angle spot meters to facilitate such measurements, because of the limited tonal range, an exposure compensation range of ±2 EV is often sufficient for using the Zone System with color film and digital sensors. Exposure value Exposure index Light meter Zone System Exposure bracketing Auto Exposure Bracketing

Film speed is the measure of a photographic film's sensitivity to light, determined by sensitometry and measured on …

This film container denotes its speed as ISO 100/21°, including both arithmetic (100 ASA) and logarithmic (21 DIN) components. The second is often dropped, making (e.g.) "ISO 100" effectively equivalent to the older ASA speed. (As is common, the "100" in the film name alludes to its ISO rating).

Digital zoom is a method of decreasing the apparent angle of view of a digital photographic or video image. Digital …

Digital zoom was used to make the middle photo from the top photo, image quality is lost, while the lens was zoomed-in optically for the bottom photo, no quality is lost. Typically, the digital zoom would not be available until after the optical zoom had been exhausted.

In photography, the metering mode refers to the way in which a camera determines the exposure. — Examples of metering... …

Honeycomb Metering on a Dynax 5D. The AF point was set to the eye of the toy; the camera has been able to produce a good exposure, by not being fooled by the strong back lighting of the out of focus areas.